In the design of circuit, the transmission of electrical signal can be achieved through a single line. However, the transmission of electrical signal will be affected by an external electric field or magnetic field, and such influence will result in signal distortion. Therefore, a duo electrically conductive line for transmitting differential signal is invented. When the differential signal is transmitted from one circuit layer to another circuit layer, the electrically conductive component is usually used to electrically connect these two circuit layers.
However, in a circuit board, a base layer (a substrate of the circuit board) has a limited area for the distribution of the circuits, so the size for the electrically conductive component is restricted. As a result, an equivalent impedance of the electrically conductive component will not match an equivalent impedance of the electrically conductive lines, which results in signal reflection while the differential signal is passing through the electrically conductive component from the circuit layer or passing through the circuit layer from the electrically conductive component, and further results in signal distortion. Especially, when the differential signal is in high frequency, the signal distortion is more severe. In order to meet the requirement of increasing amount of signal transmission, the signal reflection is an important problem to be solved in this field.